King Elementary school was locked down for about 20 minutes around 3 p.m. after the shot was fired. Students have since been dismissed.

"An anonymous caller related that two males had been in the playground area of the school. They were described as black males, one wearing a red sweatshirt, the other in a black sweatshirt. No further description was provided. One of the males fired a single shot from a handgun," a police news release stated.

Police said both males fled on foot. They were last seen heading east on Green St. from the area of Rockland Street.

Officers found one shell casing at the playground.

Here is the full news release from Lancaster police:

""On Wednesday January 15, 2014 at approximately 2:48pm Officers from the Lancaster City Bureau of Police received a call for Shots Fired in the area of Martin Luther King Elementary School, 455 S. Duke St. Lancaster, PA

An anonymous caller related that two males had been in the playground area of the school. They were described as black males, one wearing a red sweatshirt, the other in a black sweatshirt. No further description was provided. One of the males fired a single shot from a handgun. Both males fled the area on foot, last seen eastbound on Green St. from the area of Rockland St. Responding Officers canvassed the area but did not locate the suspects.

The school went into lockdown. Once it was determined that there was no longer an immediate danger to students, staff or parents the lockdown was lifted and parents were able to pick up their children at the school.

Officers located a single spent casing on the southwest corner of the school playground. Detectives are conducting follow-ups and coordinating efforts with the Lancaster Safety Coalition. Any further information on this case will come through an additional press release.

Anyone with information is urged to call Lancaster City Police at (717) 735-3300 or Lancaster City-County Crime Stoppers at 1-800-322-1913. You can also click the Submit a Tip button on our website, www.lancasterpolice.com, or Text a Tip to Crime Stoppers by texting LANCS plus your message to 847411. Tipsters may remain anonymous and do not have to give their names."